The present invention relates to a method and system for zooming a stereoscopic image appearing on an electronic display. More particularly, the present invention relates to a method and system for adjusting the disparity of a stereoscopic image appearing on an electronic display when a user zoom request is received.
The perception of depth in the planar stereo image pairs of a stereoscopic image appearing on an electronic display differs from a human's stereoscopic perception of depth in the natural world. Human stereoscopic depth perception in the natural world occurs when the left and right eyes converge their visual axes to fixate on a point while simultaneously adjusting their accommodation state through muscular action changing the focal length of the lens of each eye so that points in space at and around the fixation point come into focus. The fixation point projects to identical positions on each retina and therefore has zero retinal disparity. Points in front of or behind the fixation point project to different positions on the left and right retina. The resulting binocular disparity between the corresponding point in the left and right retinal images provides the human brain the cues from which depth may be perceived.
A key physiological difference between the perception of depth in a stereoscopic image rather than a scene in the natural world is that although the left and right eye need to converge off the stereoscopic image plane to fixate points in depth their accommodation state must always keep the image plane itself in focus. This requires that the viewer be able to alter the normal link between convergence and accommodation and is one reason why images with large perceived depth may be uncomfortable to view.
Among other factors, the perceived depth in a stereoscopic image appearing on an electronic display is directly proportional to the viewing distance to a display. Accordingly, a viewer looking at the same stereoscopic image from different distances may perceive different depth. Further, the perceived depth is also directly proportional to screen disparity (the difference in the physical horizontal coordinates of corresponding points in the left-eye and right-eye images) and which varies for any given stereoscopic image if the image is displayed at different sizes. Still further, the perceived depth is inversely proportional to a viewers individual eye separation or interpupillary distance which varies from individual to individual.
Accordingly, there is a need in the art for a method and system for adjusting the disparity of a stereoscopic image appearing on an electronic display, in general, and, more particularly, when the stereoscopic image is being altered in response to a user zoom request.